Copper cooling plate for metallurgical furnaces

ABSTRACT

A metallurgical furnace provided with a refractory lining and an outer furnace steel jacket, having copper cooling plates, wherein a flow of cooling medium flows through the cooling plates arranged between the furnace steel jacket and the refractory lining. Cooling medium pipes of the copper cooling plate provided for supplying and removing the cooling medium are guided through the furnace steel jacket to the exterior and are gas-tightly welded to the furnace steel jacket. The copper cooling plate is connected free of play in all spatial directions to the furnace steel jacket, in addition to attachment by way of the cooling medium pipes welded to the furnace steel jacket, by at least one fixed-point fastening element that is welded to the furnace steel jacket. The at least one fixed-point fastening element is arranged within at least one of the upper part and the lower part of the copper cooling plate in immediate proximity of the cooling medium pipes.

The invention relates to a copper cooling plate for metallurgicalfurnaces, such as blast furnaces, melting or melt-reduction furnaces,provided with a refractory lining and an outer furnace steel jacket,wherein a cooling medium flows through the cooling plates arrangedbetween the furnace steel jacket and the refractory lining, wherein thecooling medium pipes of the copper cooling plate provided for supplyingand removing the cooling medium are guided through the furnace steeljacket to the exterior and are gas-tightly welded to the furnace steeljacket.

Copper cooling plates (so-called Cu staves) made of copper or alow-alloy copper alloy with cooling medium channels arranged in theirinterior, manufactured by rolling, forging or casting, have normallyfour cooling medium pipes at the upper side and four cooling mediumpipes at the lower side, wherein however also fewer or more coolingmedium pipes can be provided, corresponding to the number of the coolingmedium channels that are present.

It is known to fasten cooling plates of a furnace cooling system in verydifferent ways to the inner surface of the furnace steel jacket. As aresult of the changing thermal expansion of the cooling plates atdifferent heat load, caused by the operation of the furnace, the type offastening of the cooling plates is of utmost importance.

For example, it is known from DE-C-710 923 that cooling plates, whichare secured by means of their water inlet and water outlet pipesinserted through the furnace steel jacket, are additionally suspended bysecuring and supporting cams on the furnace steel jacket.

Similarly, in U.S. Pat. No. 5,904,893 it is suggested to provide thecooling plates with a recess engaged by a supporting pin of the blastfurnace steel jacket and to suspend them in this way from the furnacesteel jacket.

In EP-A-0 837 144 the cooling plate is also suspended from the furnacesteel jacket wherein the cooling plates have hooks which engage hookswelded to the furnace steel jacket. The hooks of the cooling plate canbe formed as a rail for a better positioning of the cooling plate.

A fastening of a different type is suggested in DE-A-198 06 788. Here,the cooling plate is provided with a thread that extends through thefurnace steel jacket so that the cooling plate can be attached to thefurnace steel jacket by a screw connection.

Moreover, it is known from DE 27 43 380 A1 to fasten cooling plates madeof cast iron on the furnace steel jacket of a blast furnace by means ofscrews which are provided toward the exterior with a sealing cover. Adisadvantage of this type of fastening is that, at high heat loads ofthe cooling plates, these fastening screws expand and the cooling platescan move in the direction toward the center of the furnace so that hotfurnace gas flows through the gap between the cooling plates and thefurnace steel jacket and heats the furnace steel jacket in anuncontrolled way.

In DE 31 00 321 C1 it is therefore suggested to cast protective pipesinto the cooling plates which surround at a spacing the cooling mediumpipes in the area of the furnace steel jacket penetrations, wherein theopenings within the furnace, steel jacket are sealed against leakage offurnace gases and wherein at least one of these protective pipes servesas a stationary bearing by being welded to the furnace steel jacket andwherein further protective pipes arranged in the same plane act ashorizontally movable bearings. Moreover, at least one protective pipe,positioned opposite to the protective pipes serving as a stationarybearing, is configured as a vertically slidable bearing and theadditional protective pipes arranged in this plane are provided asmovable bearings. Each cooling medium pipe is connected by a disk with ametal compensator which is surrounded by a protective housing and isgas-tightly welded directly or by means of a pipe socket to the furnacesteel jacket in order to seal the fastening locations of the coolingplate by means of protective pipes relative to undesirable furnace gasleakage.

From 296 08 464 U1 it is known to attach the cooling plate exclusivelyby means of its cooling medium pipes to the furnace steel jacket. Inthis connection, the cooling medium pipes are guided through bores inthe furnace steel jacket and are elastically connected with the furnacesteel jacket, on the one hand, by means of a compensator welded to thepipe socket and, on the other hand, by means of a wielding connectionbetween the compensator and the cooling medium pipe.

It is an object of the invention to provide an attachment for coppercooling plates on a furnace steel jacket with which, without greaterexpenditure, the copper cooling plate can be mounted and removed andwhich makes it possible that at least some of the otherwise conventionalcompensators can be eliminated and which is also resistant to changingthermal loads.

This object is solved for a copper cooling plate of the aforementionedkind in that the copper cooling plates, in addition to the attachment bymeans of the cooling medium pipes welded to the furnace steel jacket,are connected to the furnace steel jacket by at least one fixed-pointfastening element, for example, a fastening bolt, that is welded to thefurnace steel jacket. According to the invention, two basic fasteningvariants are conceivable in this connection which can be employeddepending on the size of the copper cooling plate and the number ofcooling medium channels or cooling medium pipes.

For example, it is possible to suspend the copper cooling plate from afastening bolt or another fastening element which is located inimmediate proximity to the upper and/or lower cooling medium pipesguided through the furnace steel jacket. In this case, the fasteningelement is connected with the furnace steel jacket and the coppercooling plate such that the fastening element acts as a fixed point inall spatial directions. The immediate proximity of the fastening elementto the cooling medium pipes, on the one hand, as well as the very lowthermal expansion of the copper, on the other hand, lead to the thermalexpansions, to be expected as a result of relative temperaturefluctuations between the fastening element and the neighboring coolingmedium pipes, being so minimal that the compensators on these coolingmedium pipes can be eliminated. The cooling medium pipes can thus bewelded directly, i.e., without compensators, to the furnace steel jacketand thus provide additional fixed points. The other cooling medium pipesare fastened, as is conventional, by means of compensators on thefurnace steel jacket and provide thus movable points in all spatialdirections. The copper cooling plate is moreover connected at furthermovable points by means of corresponding fastening elements, forexample, screws with the furnace steel jacket with which movementscaused by thermal expansion are possible in the vertical/horizontaldirection.

A further variant for the attachment of the copper cooling plate residesin that the copper cooling plate is to be provided with at least onefixed point fastening element, for example, at the center of the coppercooling plate. The copper cooling plate, provided with additionalmovable point fastening elements, can then be welded entirely withoutcompensators to the furnace steel jacket wherein all cooling mediumpipes then act as additional fixed points. The thermal expansions to beexpected between the fixed points, provided in this way, are so minimalthat they can be neglected and no compensators are therefore required.The elimination of the compensators provides a significant advantage asa result of the reduced mounting and welding expenditure because acompensator would have to be welded in a gas-tight way, on the one hand,to the furnace steel jacket and, on the other hand, to the pipe socketof the copper cooling plate.

Those cooling medium pipes which do not require compensators accordingto the invention are gas-tightly welded from the exterior directly ontothe furnace steel jacket and are arranged either by means of aperforated template or by means of a simple cylindrical cup whichenlarges the spacing of the fixed point of the welded cooling mediumpipe relative to the body of the copper cooling plate even more.

With the attachment of the copper cooling plate according to theinvention it is thus possible to mount copper cooling plates onmetallurgical furnaces, in particular, blast furnaces or other meltingand melt-reduction furnaces, in a simpler, faster, and less expensiveway.

Further advantages, features, and details of the invention will beexplained in more detail in the following with the aid of embodimentsillustrated in the schematic drawing figures, wherein identicalconstruction parts are identified with identical reference numerals. Itis shown in:

FIG. 1 a plan view at the connecting side onto a copper cooling platewith one fixed-point fastening element arranged at the top,

FIG. 2 a side view of the copper cooling plate with furnace steel jacketaccording to FIG. 1,

FIG. 3 a plan view onto the connecting side of a copper cooling platewith two fixed-point fastening elements arranged at the center of thecopper cooling plate,

FIG. 4 a side view of the copper cooling plate with furnace steel jacketaccording to FIG. 3.

In FIGS. 1 and 2 a plan view (FIG. 1) and a side view (FIG. 2) of thecopper cooling plate 10 with four cooling medium channels (not shown)are illustrated whose cooling medium pipes 13, 14 for supplying andremoving the cooling medium are arranged at the upper part and the lowerpart of the copper cooling plate 10. In immediate proximity of the uppercooling medium pipe 13 a fastening bolt as a fixed-point fasteningelement 11 is arranged which is welded with a washer 17 onto the furnacesteel jacket 15.

As a result of the spatial proximity of the fixed-point fasteningelement 11 to the cooling medium pipes 13, these cooling medium pipes 13can be welded directly, without the otherwise conventional compensators,onto the furnace steel jacket 15 with a washer 17.

The lower cooling medium pipes 14, which are moved spatially too farfrom the fixed-point fastening element 11, are connected in an unchangedway with compensators 16 to the furnace steel jacket 15.

Moreover, several movable point fastening elements 12, in the form offastening screws in this embodiment, are arranged across the surface ofthe copper cooling plates 10 in a symmetrical distribution for thepurpose of an additional attachment of the copper cooling plates 10 onthe furnace steel jacket 15.

By means of the attachment according to the invention of the coppercooling plate 10 on the furnace steel jacket 15, the forces resultingfrom thermal expansion are received without problem wherein the uppercooling medium pipes 13 and the fastening bolt 11 are fixed points, thelower cooling medium pipes 14 with compensators 16 are movable pointsmovable in all spatial directions, and the fastening screws 12 act alsoas movable points in the vertical/horizontal direction.

In FIGS. 3 and 4 in a plan view (FIG. 3) and in a side view (FIG. 4) afurther fastening type or embodiment according to the invention of acopper cooling plate 10′ in connection with the furnace steel jacket 15is illustrated. In this embodiment, two fixed-point fasting elements 11(fastening bolts) are arranged at the center of the copper cooling plate10′. In addition, as also disclosed in the embodiment of FIGS. 1 and 2,further moveable point fasting elements 12 (fasting screws) are present.In this fasting variant illustrated in FIGS. 3 and 4, all compensatorscan be eliminated because the relative thermal expansions between thefixed-point fasting elements and the fixed positions of the upper andalso the lower cooling medium pipes 13 are so minimal that they can beneglected. The attachment of the copper cooling plate 10′ in this casethus is comprised of the fixed points of the fastening bolts 11 and thewelded cooling medium pipes 13, 14 as well as the movable points (invertical/horizontal direction) of the fastening screws 12.

The invention is not limited to the illustrated embodiments; instead, inparticular, with respect to the number and arrangement of thefixed-point and moveable point fasting elements as well as theirconfiguration as bolts or screws, variants that depend on the size ofthe copper cooling plate are possible, as long as they enable theelimination of compensators in accordance with the invention.

1. A metallurgical furnace, such as a blast furnace, melting ormelt-reduction furnace, provided with a refractory lining and an outerfurnace steel jacket (15), comprising copper cooling plates (10, 10′),wherein a flow of cooling medium flows through the cooling platesarranged between the furnace steel jacket (15) and the refractorylining, wherein cooling medium pipes (13, 14) of the copper coolingplate (10, 10′) provided for supplying and removing the cooling mediumare guided through the furnace steel jacket (15) to the exterior and aregas-tightly welded to the furnace steel jacket (15), wherein the coppercooling plate (10, 10′) is connected free of play in all spatialdirections to the furnace steel jacket (15), in addition to attachmentby means of the cooling medium pipes (13, 14) welded to the furnacesteel jacket (15), by at least one fixed-point fastening element (11)that is welded to the furnace steel jacket (15), the at least onefixed-point fastening element being arranged within at least one of theupper part and the lower part of the copper cooling plate immediateproximity of the cooling medium pipes.
 2. A metallurgical furnace, suchas a blast furnace, melting or melt-reduction furnace, provided with arefractory lining and an outer furnace steel jacket (15), comprisingcopper cooling plates (10, 10′), wherein a flow of cooling medium flowsthrough the cooling plates arranged between the furnace steel jacket(15) and the refractory lining, wherein cooling medium pipes (13, 14) ofthe copper cooling plate (10, 10′) provided for supplying and removingthe cooling medium are guided through the furnace steel jacket (15) tothe exterior and are gas-tightly welded to the furnace steel jacket(15), wherein the copper cooling plate (10, 10′) is connected free ofplay in all spatial directions to the furnace steel jacket (15), inaddition to attachment by means of the cooling medium pipes (13, 14)welded to the furnace steel jacket (15), by at least one fixed-pointfastening element (11) that is welded to the furnace steel jacket (15),at least one of the fixed-point fastening elements (11) being arrangedat the center of the copper cooling plate (10, 10′).
 3. Themetallurgical furnace according to claim 1, wherein the copper coolingplate (10, 10′) is additionally fastened fixedly to the furnace steeljacket (15) by at least one movable point fastening element (12), forexample, a fastening screw, which allows thermal expansion movements ofthe copper cooling plate (10, 10′) in the horizontal and verticaldirection.
 4. The metallurgical furnace according to claim 2, whereinthe copper cooling plate (10, 10′) is additionally fastened fixedly tothe furnace steel jacket (15) by at least one movable point fasteningelement (12), for example, a fastening screw, which allows thermalexpansion movements of the copper cooling plate (10, 10′) in thehorizontal and vertical direction.
 5. The metallurgical furnaceaccording to claim 1, wherein at least some of the cooling medium pipes(13, 14) are welded without use of a compensator directly to the furnacesteel jacket (15).
 6. The metallurgical furnace according to claim 2,wherein at least some of the cooling medium pipes (13, 14) are weldedwithout use of a compensator directly to the furnace steel jacket (15).